Mitosis

During mitosis, the
chromatids on each
chromosome are
physically moved to
opposite sides of the
dividing cell with help
of the spindle fibers.

Spindles are cell
structures made up of
both centrioles and
individual
microtubule fibers
that are involved in
moving chromosomes
during cell division.


When a cell enters the
mitotic phase, the
centriole pairs start to
separate, moving
toward opposite poles
of the cell.
As the centrioles move
apart, the spindle
begins to form.

The chromatids are
moved to each pole
of the cell in a
manner similar to
bringing in a fish
with a fishing rod
and reel.


When the
microtubule
“fishing line” is
“reeled in” the
chromatids are
dragged to
opposite poles.
As soon as the
chromatids
separate from each
other they are
called
chromosomes.

Step 1: Prophase:
 Nuclear envelope
dissolves.
 Chromosomes coil
and condenses, thus
becoming visible.
 Spindle fibers
form.

Step 2: Metaphase
 Chromosomes
move to the
equator of the cell.

Step 3: Anaphase
 Chromotids
divide at the
centromere and
move to
opposite poles.

Step 4: Telophase
 Nuclear envelope
reforms.
 Chromosomes
uncoil and
disappear.
 Pinching of parent
cell begins.


As mitosis ends,
cytokinesis begins.
During cytokinesis, the
cytoplasm of the cell is
divided in half, and the
cell membrane grows to
enclose each cell,
forming two daughter
cells as a result.

The end result of
mitosis and
cytokinesis is two
genetically identical
cells where only one
cell existed before.